Switching circuitry

Abstract

The present invention relates to switching circuitry wherein a low-loss "drive" inductance is "charged" and "discharged" to provide the energy for turning a power switch on and off. The drive-inductance and a tapped-winding transformer co-act in a novel manner to provide a large "sweep-out" current that quickly turns off the power switch, the sweep-out time being extremely short.

I claim: 
     
       1. Switching circuitry comprising: a control switch;   a drive circuit comprising a charge circuit and a discharge circuit;   a drive inductor;   a drive transformer;   said drive transformer having a charge primary winding, a discharge primary winding, and a secondary winding;   said charge circuit comprising said secondary winding and a series circuit of said drive inductor, said control switch, and said charge primary winding;   whereby when said control switch assumes its ON state, a charge current in said charge circuit charges said drive inductor, and produces an enabling signal in said secondary winding;   a power switch adapted to permit the flow of an electric current therethrough;   means for applying said enabling signal to said power switch, for causing said power switch to quickly and positively assume its ON state and for permitting the flow of a load current;   said discharge circuit comprising said secondary winding and a series circuit of said drive inductor and said discharge primary winding;   whereby, when said control switch assumes its OFF state, the energy of said charged drive inductor directly produces a discharge current, and said discharge current in said discharge circuit produces a disabling signal in said secondary winding;   means for applying said disabling signal to said power switch for causing said power switch to quickly and positively assume its OFF state, and for terminating the flow of the load current.   
     
     
       2. The invention of claim 1, wherein said control switch and said power switch are transistors. 
     
     
       3. The invention of claim 1, wherein said discharge circuit further comprises blocking diode means for blocking said charge current from flowing in said discharge circuit. 
     
     
       4. The invention of claim 1, including a second drive circuit; means for causing said power switch to function as a control switch for said second drive circuit,   whereby said drive circuits are cascaded.   
     
     
       5. The invention of claim 1, including a plurality of control switches, a corresponding plurality of drive circuits associated with respective ones of said control switches, and a corresponding plurality of power switches associated with respective ones of said drive circuits; means for causing said control-circuit means to conductivate said individual control switches of said plurality of control switches in a sequential timed manner;   whereby said individual drive circuits and said individual power switches are energized in a corresponding sequential timed manner.   
     
     
       6. Switching circuitry comprising: a control transistor;   control-circuit means for controlling the ON/OFF state of said control transistor;   a drive circuit comprising a charge circuit and a discharge circuit;   a drive inductor;   a drive transformer;   said drive transformer having a charge primary winding, a discharge primary winding, and a secondary winding;   said charge circuit comprising said secondary winding, blocking diode means for blocking said charge current from flowing in said discharge circuit and a series circuit of said drive inductor, said control switch, and said charge primary winding;   whereby, when said control transistor assumes its ON state, a charge current in said charge circuit charges said drive inductor, and produces an enabling signal in said secondary winding;   a power transistor adapted for the flow of an electric current therethrough;   means for applying said enabling signal to said power transistor, for causing said power transistor to quickly and positively assume its ON state;   said discharge circuit comprising said said secondary winding and a series circuit of said drive inductor and said discharge primary winding;   whereby, when said control transistor assumes its OFF state, the energy of said charged drive inductor directly produces a discharge current, and said discharge current in said discharge circuit produces an opposite-polarity disabling signal in said secondary winding;   said disabling signal being a short-interval, high-magnitude, sweep-out current;   means for applying said disabling signal to said power transistor for causing said power transistor to quickly and positively assume its OFF state.   
     
     
       7. The invention of claim 6, including means for controlling the timing of said control circuit means.